Abstract
Black individuals are at greater risk for the development of cardiovascular diseases compared to White individuals. Autonomic nervous system (ANS) dysregulation has been identified as a significant risk factor contributing to racial disparities in cardiovascular disease, yet systematic racial differences that affect the measurement of ANS activity among White and Black participants are likely obscuring understanding about ANS-health disparity links. Moreover, sex differences in ANS activity have been observed. Thus, efforts to elucidate the comparability of ANS indices across race and sex are needed. This study aimed to investigate the effects of race and sex on the associations between two indices of ANS activity-cardiac vagal activity and urinary catecholamines-in a sample of White and Black participants from the MIDUS 2: Biomarker Project (N = 967 adults aged 34 - 84; 81 % White, 57 % female). Participants self-reported their sociodemographic and health information and completed biomarker assessments. Cardiac vagal activity was assessed via heart rate (HR) and heart rate variability (HRV); urinary catecholamines were assessed via epinephrine and norepinephrine. Black participants displayed higher HRV activity and lower levels of urinary catecholamines relative to White participants. Moreover, our results revealed small but significant correlations between urinary catecholamines and cardiac vagal activity across both races, though the nature of these relations varied across race, sex, and ANS index. The correlations between HR and epinephrine and norepinephrine were stronger among Black male participants compared to White male participants. Our results highlight the importance of clarifying the functional equivalence of different ANS indices across race and sex.